Abstract: The invention relates to a method and instrument for the fragmentation of large molecular analyte ions, preferably biopolymer ions, by reactions between multiply charged positive analyte ions and negative reactant ions in RF quadrupole ion traps. Some of these reactions involve electron transfer reactions with subsequent dissociation of the biopolymer analyte ions, and some involve the loss of a proton, leading to stable product ions. The invention can use any type of ion traps, particularly three-dimensional RF quadrupole ion traps, for the reactions between positive and negative ions. The fragmentation yield can be increased because ions that remain stable as radical cations after transfer of an electron are further fragmented by collisionally induced fragmentation, forming fragment ions that are typical of electron transfer, and not those typical of collisionally induced fragmentation.

Abstract: The invention relates to RF voltage-operated ion guides based on stacked apertured diaphragms. The invention provides ion guides consisting of diaphragm stacks that permit the ion beam to be shaped in cross-section so that it corresponds to the acceptance profile of the subsequent section of the device, therefore yielding optimal ion transmission. For this purpose, at least some of the diaphragms in the diaphragm stacks do not have circular openings, but instead have openings which shape the cross section of the emerging ion beam in the desired manner. It is possible, for instance, to obtain elliptical beam cross sections, divided beams or beams focused to the shape of a fine thread at the output of the diaphragm stacks.

Abstract: In an RF ion trap, analyte ions are fragmented by applying a moderately high RF storage voltage to the trap. The ions are then excited via dipolar excitation, and after a short time, the ions are forced into a resting state, again using dipolar excitation. The RF storage voltage is then rapidly reduced to a low value thereby making it possible to store small fragment ions produced by ergodic decompositions that occur subsequent to the reduction of the RF storage voltage.

Abstract: The invention relates to methods for the measurement of fragment ion spectra in ion trap mass spectrometers in which fragment ions below a cut-off mass cannot normally be measured. The invention consists in measuring mass spectra including light fragment ions by briefly conducting the collisionally induced fragmentation—which is always brought about by a large number of collisions—at an unusual high RF storage voltage, which produces collisions more energetically than by conventional fragmentation, and then switching the RF voltage to a low RF voltage in a fast but controlled procedure. In this way light fragment ions are produced by double cleavages from metastable fragment ions with a certain half-life time. Since the cut-off mass for the storage capability is proportional to the RF storage voltage, reducing the RF storage voltage means that the light fragment ions can also be kept and measured in the ion trap.

Abstract: The invention relates to methods and devices for the transport of ions generated in gases near atmospheric pressure into the vacuum system of a mass spectrometer. Instead of the single capillary customary in commercial instruments, the invention uses a multichannel plate with hundreds of thousands of very short and narrow capillaries, whose total gas throughput is no higher than that of a normal single capillary. The large-area take-up of ions in the gas flow greatly increases the transfer yield. If the channels are conductive, this prevents the inside surfaces becoming charged. An ion funnel can separate the ions from the gas flow in the vacuum and focus them. Gas-dynamic focusing in an electric decelerating field reduces ion losses caused by wall collisions and prevents very light ions (protons, water clusters) from entering the vacuum. Staged multichannel plates reduce pumping requirements.

Abstract: The invention relates to a method and instrument for the fragmentation of large molecular analyte ions, preferably biopolymer ions, by reactions between multiply charged positive analyte ions and negative reactant ions in RF quadrupole ion traps. Some of these reactions involve electron transfer reactions with subsequent dissociation of the biopolymer analyte ions, and some involve the loss of a proton, leading to stable product ions. The invention can use any type of ion traps, particularly three-dimensional RF quadrupole ion traps, for the reactions between positive and negative ions. The fragmentation yield can be increased because ions that remain stable as radical cations after transfer of an electron are further fragmented by collisionally induced fragmentation, forming fragment ions that are typical of electron transfer, and not those typical of collisionally induced fragmentation.

Abstract: The invention relates to RF voltage-operated ion guides based on stacked apertured diaphragms. The invention provides ion guides consisting of diaphragm stacks that permit the ion beam to be shaped in cross-section so that it corresponds to the acceptance profile of the subsequent section of the device, therefore yielding optimal ion transmission. For this purpose, at least some of the diaphragms in the diaphragm stacks do not have circular openings, but instead have openings which shape the cross section of the emerging ion beam in the desired manner. It is possible, for instance, to obtain elliptical beam cross sections, divided beams or beams focused to the shape of a fine thread at the output of the diaphragm stacks.

Abstract: The invention relates to the removal of electronic noise from mass spectra which are scanned as single spectra and added together to give a sum spectrum. The invention consists in removing the noise in the single spectra and not in the sum spectrum since ion signals and electronic noise can only be distinguished in the single spectra.

Abstract: The invention relates to ion-guide systems for the transfer, cooling, fragmentation, selection and temporary storage of ions. The invention consists in embedding systems, made from one or more straight or curved rods to which a single or multiphase radio frequency voltage is applied, in an external enveloping dc potential. The combination of the ion-repelling radio-frequency pseudo field around the rods and the external dc voltage field represents a new category of ion-guide systems. With external dc voltage fields, whose strength or penetration into the interior of the rod system varies along the axis of the system, the ions can be collected or propelled along the axis of the system. Filling the system with collision or damping gas allows the ions to be fragmented and cooled without any losses and the phase space volumes of the ions to be greatly reduced.

Abstract: The invention relates to the control of the filling process of an ion trap with ions in order to avoid the deteriorating effect of too many stored ions on the quality of the spectrum during a mass scan. In the prior art, the “number of ions” inside the ion trap were used to contol filling. However, controlling the number of ions does not provide optimum trap filling for different ion compositions. The invention overcomes the problem by controlling a mass-dependent physical parameter and applying an cluster-dependent target value. This method takes into account the mass-dependency of optimum ion filling as well as the effect of non-uniform distribution of ions of different mass-to-charge ratios over the mass spectrum.

Abstract: The invention relates to ion-guide systems for the transfer, cooling, fragmentation, selection and temporary storage of ions. The invention consists in embedding systems, made from one or more straight or curved rods to which a single or multiphase radio frequency voltage is applied, in an external enveloping dc potential. The combination of the ion-repelling radio-frequency pseudo field around the rods and the external dc voltage field represents a new category of ion-guide systems. With external dc voltage fields, whose strength or penetration into the interior of the rod system varies along the axis of the system, the ions can be collected or propelled along the axis of the system. Filling the system with collision or damping gas allows the ions to be fragmented and cooled without any losses and the phase space volumes of the ions to be greatly reduced.

Abstract: The invention relates to the removal of electronic noise from mass spectra which are scanned as single spectra and added together to give a sum spectrum. The invention consists in removing the noise in the single spectra and not in the sum spectrum since ion signals and electronic noise can only be distinguished in the single spectra.

Abstract: The invention relates to the fragmentation of ions in ion traps filled with collision gas by exciting their axial oscillations in a dipole-shaped excitation field with a frequency mixture which covers the frequency of ion oscillations. The invention consists of ramping up the voltages of the frequency mixture for the dipolar excitation field, as a result of which, surprisingly, approximately the same fragmentation results are obtained for ions of different structures in the same fragmentation times as at a structurally specific optimal voltage applied at a constant level.